Program to find sum of series 1 + 2 + 2 + 3 + 3 + 3 + . . . + n | C # Program to find sum of series 1 + 2 + 2 + 3 + . . . + n ; Function that find sum of series . ; Driver Code
using System ; public class GfG { static int sumOfSeries ( int n ) { return ( n * ( n + 1 ) * ( 2 * n + 1 ) ) / 6 ; } public static void Main ( ) { int n = 10 ; Console . WriteLine ( sumOfSeries ( n ) ) ; } }